Adding/recovering packet number using packet_utils python cl


#1

Hi,

I was wondering if we can add the packet number using current
packet_utils
python class.

When I look into the code, I see that we introduce the preamble, access
code, length of the packet, payoad with crc, and padding for usrp using
make_packet function. At the same time when I look into the pkt.py , I
see
that msg.to_string() is the whitened_payload_with_crc and msg.arg1() is
the
whitener_offset for unmake_packet function in packet_utils class.

Now, I understand that the preamble and access codes are removed by the
timing and frequncy sync blocks in the receiver (please correct me if I
am
wrong), but I could not understand where the packet length, attached
with
the transmitted packet, went or if it was present, how do I get that?

Well, if I add the packet sequence number in the transmitted packet, how
can
i recover the sequence number? is it possible with current packet_utils
python class or I need to write a new class for the same?

I would welcome any guidance over adding/recovering of packet sequence
number.

Thanks in advance.

~Tarun
UT Dallas


#2

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Tarun T. wrote:

Now, I understand that the preamble and access codes are removed by the
timing and frequncy sync blocks in the receiver (please correct me if I am
wrong), but I could not understand where the packet length, attached with
the transmitted packet, went or if it was present, how do I get that?

A better way to put it is that the preamble is ignored altogether and
the access code is detected by the framer_sink, which then pulls off the
length field.

Well, if I add the packet sequence number in the transmitted packet, how
can
i recover the sequence number? is it possible with current packet_utils
python class or I need to write a new class for the same?

Why don’t you just put the sequence number as part of the body of the
message and then you don’t have to touch packet_utils?

  • -Dan
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